• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.390-396
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• 2010

An 80MHz surface acoustic wave (SAW)-based gyroscope utilizing a progressive wave was developed on a piezoelectric substrate. The developed sensor consists of two SAW oscillators in which one is used for sensing element and has metallic dots in the cavity between input and output IDTs. The other is used for a reference element. Coupling of mode (COM) modeling was conducted to determine the optimal device parameters prior to fabrication. According to the simulation results, the device was fabricated and then measured on a rate table. When the device was subjected to an angular rotation, oscillation frequency differences between the two oscillators were observed because of the Coriolis force acting on the metallic dots. Depending on the angular rate, the difference of the oscillation frequency was modulated. The obtained sensitivity was approximately 52.35 Hz/deg.s within the angular rate range of 0~1000 deg/s. The performances of devices with three IDT structures for two kinds of piezoelectric substrates were characterized. Good thermal stability was also observed during the evaluation process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.899-900
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• 2009

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.54-62
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• 2013

In this study, a wireless and non-power SAW (surface acoustic wave) temperature sensor was developed. The single inter-digital transducer (IDT) of SAW temperature sensor of which resonance frequency is 434 MHz was fabricated on $128^{\circ}$ rot-X $LiNbO_3$ piezoelectric substrate by semiconductor processing technology. To find optimal acoustic reflector for SAW temperature sensor, various kinds of acoustic reflectors were fabricated and their reflection characteristics were analyzed. The IDT type acoustic reflector showed better reflection characteristic than other reflectors. The wireless temperature sensing system consisting of SAW temperature sensor with dipole antenna and a microprocessor based control circuit with dipole antenna for transmitting signal to activate the SAW temperature sensor and receiving the signal from SAW temperature sensor was developed. The result with wireless SAW temperature sensing system showed that the frequency of SAW temperature sensor was linearly decreased with the increase of temperature in the range of 40 to $80^{\circ}C$ and the developed wireless SAW temperature sensing system showed the excellent performance with the coefficient of determination of 0.99.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.6
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• pp.375-381
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• 2021

This paper investigated sound characteristics by the delamination of an acoustic window. In detail, acoustic scattering and transmission characteristics on the delaminated acoustic window were estimated using an experimental and numerical approach. The experiment results showed that acoustic wave could lose its amplitude and take phase delay when it propagates the delaminated acoustic window. The numerical results showed that scattering phenomena occur on the delamination surface. The scattering characteristics presented differently according to the delamination size in the acoustic window. It also showed that transmitted sound distortion due to delamination could cause a direction detection error of SONAR by changing the position of the main lobe and the magnitude of the side lobe. In conclusion, the delamination has to be managed during the manufacturing process of acoustic windows.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.10 s.115
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• pp.1057-1066
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• 2006

Acoustic streaming Induced by longitudinal vibration at 30 kHz is visualized for a test fluid flow between the stationary glass plate and ultrasonic vibrating surface with particle imaging velocimetry (PIV) To measure an increase in the velocity of air flow due to acoustic streaming, the velocity of air flow in a gap between the heat source and ultrasonic vibrator is obtained quantitatively using PIV. The ultrasonic wave propagating into air in the gap generates steady-state secondary vortex called acoustic streaming which enhances convective cooling of the stationary heat source. Heat transfer through air in the gap is represented by experimental convective heat transfer coefficient with respect to the gap. Theoretical analysis shows that gaps for maximum heat transfer enhancement are the multiple of half wavelength. Optimal gaps for the actual design are experimentally found to be half wavelength and one wavelength. A drastic temperature variation exists for the local axial direction of the vibrator according to the measurement of the temperature distribution in the gap. The acoustic streaming velocity of the test fluid in the gap is at maximum when the gap agrees with the multiples of half wavelength of the ultrasonic wave, which are specifically 6 mm and 12 mm.

• Journal of electromagnetic engineering and science
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• v.6 no.2
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• pp.110-116
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• 2006

A reflective array type surface acoustic wave(SAW) dispersive delay line(DDL) with high time-bandwidth at the V/UHF-band is designed and fabricated for compressive receiver applications. This type of the SAW DDL has the properties of the relative bandwidth of 20 %, the time delay of 49.89 usec, the insertion loss of 38.5 dB and the side lobe rejection of 39 dB. In comparison with a commercial SAW DDL, the insertion loss, amplitude ripple and side lobe rejection are improved by $1.5dB{\pm}0.6dB$ and 4 dB respectively. Using the fabricated SAW DDL, the prototype of the compressive receiver is developed. It is composed of RF converter, fast tunable LO, chirp LO, A/D converter, signal processing unit and control unit. This prototype system shows a fine frequency resolution of below 30 kHz with high scan rate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.251-252
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• 2006

A development of surface acoustic wave gas sensor to detecting volatile gas has been observed by monitoring output signal as function of time onto the network analyzer. The SAW sensor with a center frequency of 200MHz was fabricated on $42^{\circ}$ S-T Quartz substrates. Using the gas chromatography column has been selectivity. Experimental results, which show the phase change of output signal under the absorption of volatile gas onto sensors, were presented. The proposed sensor has the properties of high sensitivity compare to the conventional SAW gas sensor and chemical selectivity. Thus, it is thought these results are applicable for use in sensor array of an high performance electronic nose system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.12
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• pp.597-600
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• 2002

Film Bulk Acoustic wave Resonator (FBAR) using thin piezoelectric films can be made as monolithic integrated devices with compatibility to semiconductor process, leading to small size and low cost, high Q RF circuit elements with wide applications in communications area. This paper presents a MMIC compatible suspended FBAR using surface micromachining. Membrane is composed $Si_3N_4SiO_2Si _3N_4$ multi layer and air gap is about 50${\mu}{\textrm}{m}$. Firstly, We perform one dimensional simulation applying transmission line theorem to verify resonance characteristic of the FBAR. Process of the FBAR is used MEMS technology. Fabricated FBAR resonate at 2.4GHz, $K^2_{eff}$ and Q are 4.1% and 1100.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.77-79
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• 2003

The stability of flows induced by a surface acoustic wave (SAW) propagating along the deformable walls in a confined parallel-plane microchannel or slab in the laminar flow regime is investigated. The governing equation which was derived by considering the nonlinear coupling between the deformable or waving interface and viscous fluids is linearized and then the problem is solved by a verified code based on the spectral method together with the associated interface and boundary conditions. The value of the critical Reynolds number was found to be near 1439 which is much smaller than the rigid-wall case: 5772 for conventional pressure-driven flows.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.139-145
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• 2006

This paper presents the design and manufacturing of a sensor using SAW and delay line in order to measure temperature. SAW sensors having single and double electrodes are manufactured on the $128^{\circ}YX-LiNbO_3$ substrate, and its process is addressed. Before manufacturing, the device is simulated using a commercial finite element program. The frequency responses of the saw sensor on the temperature change is measured. Since the center frequency on the temperature change from $-30^{\circ}C$ to $80^{\circ}C$ is linearly changed, the saw sensor is applicable to measure the temperature change or strain variation.